Carburetor



Jan. 15, 1957 s. M. UDALE 2,777,678

CARBURETOR Filed July 28, 1955 INVENTOR.

1 2,777,678 CARBURETOR Stanley M. Udale, Detroit, Mich, assignor toHolley Carburetor Company, Detroit, Mich., a corporation of MichiganApplication July 28, 1953, Serial No. 370,724 3 Claims. (Cl. 26141) Theobject of this invention is to improve the range of octane fuels withwhich a carburetor will work. This is accomplished by having the venturiautomatically open up at high speeds so as to provide the simplestpossible carburetor which will permit the highest possible compressionratio with a given fuel without knocking. The venturi into which thefuel nozzle discharges should open up automatically as the load isreduced and the engine speed increases. At the same time the area of thefuel orifice must be increased as the fuel ratio must remain at alltimes within narrow limits. At wide open throttle the fuel mixture istaken care of by a well known fuel economizer responsive to inletmanifold suction. At maximum compression and at maximum air flow themixture must be slightly richer than 14 to 1 to permit maximumcompression free from knocking.

An offset choke in the throat of the venturi upstream of the fuel nozzleand spring loaded and connected to a fuel needle valve is the solutionof this problem. Air flow thus opens the choke and fuel valvesimultaneously.

In the figure:

A is the air entrance.

B is the venturi in A.

C is the choke valve eccentrically mounted on a shaft Y and having itsdownstream lip slightly curved so that the choke valve blows openeventually.

D is the fuel nozzle discharging into B downstream of C.

E is the normal fuel orifice leading out of the float chamber L and sosupplying fuel to the passage T and to the low speed fuel tube Q and tothe two low speed fuel outlets R and S controlled by the throttle P in awell-known manner.

F is a cam mounted on the choke shaft Y which engages a roller H on theend of the lever I so shaped as to permit the valve C to blow wide open.

K is a compression spring engaging a needle valve G Which is lifted bythe lever I when the choke valve C is opened. Needle valve G opens up apassage for fuel so as to add more fuel to that supplied by orifice E.

Valve M is the fuel for wide open throttle admitted when the pressure atopening in the mixture outlet rises and spring U acting againstdiaphragm N then opens valve M in a well known manner.

A choke control rod V, when moved to the right, closes choke valve Cpositively by collapsing the spring W. It will be noted that althoughthe fuel needle G closes whenever the choke valve C is closed, thenormal fuel orifice E always remains wide open to provide the stare ingfuel.

When choke control rod V is moved to the left the spring W permits thecam F to raise the needle valve G as the valve C opens. As the speed ofthe engine increases the choke C is blown more and more open and theneedle valve admits more and more fuel and eventually valve C is blownwide open and the cam F raises the roller H and lifts the needle valve Gto admit the maximum amount of fuel. At the same time, as the throttle Pis eventually opened wide, the pressure at opening 0 rises and the valveM also rises.

It will be noted that as the choke valve is blown open the choke lever Zis moved to the left to compress the spring W; hence, the position ofthe rod V can be used to reduce knocking.

nite rates Patent 0 2,777,678 Patented Jan. 15,1957

Unlike all air valve carburetors, this air valve carburetor does notdepend on the characteristic of the compression of the springs W and Kto determine the fuel air ratio. So long as the air flow through theventuri B around the choke valve C does not approach a high value (speedof sound, for example) the depression causing fuel flow from nozzle Dthrough orifice E and past the needle valve G will correspond to theairflow. Hence, if the engine knocks and the knocking is reduced byadvancing the rod V to the right but not far enough to the right toactually choke the engine, the torque developed by the engine will bereduced at low engine speeds with throttle P wide open; but the mixturewill not become excessively rich; on the other hand, if high octane fuelis used and the rod V is moved over to the left so that the choke Copens up at a lower engine speed, the mixture will not becomeexcessively lean as is the case when the spring load on an ordinary airvalve carburetor in common use thirty to forty years ago.

This is a continuation in part of my case filed July 15, 1953, SerialNo. 368,142, now Pat. No. 2,741,466, issued April 10, 1956, in the nameof Stanley M. Udale and an assignment to the Holley Carburetor Company.

What I claim is:

1. In a carburetor of the variable venturi type having a constant levelfuel supply chamber, an air entrance of venturi form, a shaftunsymmetrically located transversely through the throat thereof, anunbalanced butterfly valve mounted on said shaft and having itsdownstream wing longer than its upstream wing, a fuel nozzle connectedto said fuel chamber and having its discharge outlet in said throatbelow said upstream wing, a mixture outlet having a manually controlledthrottle valve therein, a second fuel nozzle also connected to said fuelchamber and having a double fuel outlet divided by said throttle valvewhen in its idling position so that the discharge from the said secondnozzle increases as the throttle is moved away from its idling position,a fixed fuel orifice supplying fuel to the first mentioned nozzle, avariable fuel orifice and a needle valve therefor, said variable orificesupplementing the supply of fuel from said fixed orifice to said firstmentioned nozzle, mechanical linkage interposed between said needlevalve and said unbalanced butterfly valve so arranged that as theunbalanced butterfly valve is sucked open after the throttle has beenopened the needle valve is moved to admit more fuel to the firstmentioned nozzle, yieldable means adapted to oppose opening of both theunbalanced butterfly valve and of the fuel controlling needle valve.

2. A device as set forth in claim 1 in which there are manually operatedover-riding means to close the throat of said venturi for starting.

3. A device as set forth in claim 1 in which the said mechanical linkagecomprises a cam mounted on said shaft outside said venturi throat, aroller that rides on said cam, a lever to which said roller is connectedso that it can rotate a fulcrum for said lever, a mechanical connectionfrom said lever to said needle valve transmitting the yieldable means toforce the roller to engage said cam.

References Cited in the file of this patent UNITED STATES PATENTS1,872,559 Bicknell Aug. 16, 1932 1,900,191 Mock Mar. 7, 1933 2,004,242Heitger June 11, 1935 2,167,892 Kent et al Aug. 1, 1939 2,407,534Carlson Sept. 10, 1946 2,479,392 Miller Aug. 16, 1949 2,499,554 WirthMar. 7, 1950 2,631,832 Hieger Mar. 17, 1953 2,646,264 Morris July 21,1953

